The present invention relates to a method and an apparatus for manufacturing a steel cord, and more particularly to a method and an apparatus for manufacturing a steel cord which is capable of enhancing the double twist pattern up to four times or six times compared to the prior art by arranging plural pairs of flyers to a twisting unit of the steel cord.
The steel cord is made of a plurality of metal filaments which are carbon steel containing 0.6 to 1.0 percent in weight of carbon and having diameters of 0.1 to 0.4 mm, and which are coated with brass of 0.1 to 0.4 in thickness. The steel filaments are twisted in various patterns according to its use, such as patterns of 1.times.2, 1.times.3, 1.times.4, 2+2, 3+6, and 3+9+15. The steel cord is superior to other inorganic fibers and organic fibers in terms of strength, modulus, thermal resistance, fatigue resistance, etc. Accordingly, the steel cord is primarily used as a reinforcing member for a rubber product, such as a tire.
Generally, the steel cord is manufactured as follows. Selected two or more steel filaments are twisted by the twisting unit of the braiding machine, discharged by the discharging unit, and then wound. The braiding machine for manufacturing the steel cord as mentioned above roughly comprises a filament supplying unit, a twisting unit for twisting a plurality of filaments supplied from the filament supplying unit, a discharging unit for discharging the twisted cord, and winding unit for winding the discharged cord under the fixed tension.
FIG. 1 shows an apparatus for manufacturing a double steel cord of the prior art. As shown in FIG. 1, there is provided a twisting unit including elements which rotate in the same direction and the same angular velocity, the rotating elements consisting of first turn roller 11 arranged at the inlet, second turn roller 12 arranged at the outlet, and a pair of flyers 9, 10 arranged at the inlet and the outlet, respectively.
During the operation of the aforementioned apparatus, the rotating elements rotates counterclockwise in a view of direction from inlet to outlet.
More particularly, as shown in FIG. 1, steel filaments 2 wound on the steel filament bobbin 1 which corresponds to the aforementioned filament supplying unit, are unwound, pass through filament guide rollers 3, 4 respectively, and combined by means of a guide roller 5. The combined two steel filaments 2 is directed to the first turn roller 11 via a guide roller 6. At this time, by the rotation of the flyers 9, 10 at the area between the first turn roller 11 and the second turn roller 12, the twist pitch is applied to the steel cord to form a twist pattern in one direction. Then the cord from the flyers 9, 10 is guided to an overtwister 13, a discharging capstan 14, correcting unit 15, and a guide roller 16 via the second turn roller, 12. Finally, the cord is wound by means of a winding unit 17.
In the apparatus for manufacturing steel cords, productivity depends on the twist pattern of the filaments formed by the twisting unit for twisting the filaments supplied from the filament supplying unit. However, the braiding machine of the prior art as mentioned above has problems that it is not possible to change the twist pattern easily since the twist patterns are predetermined as single or double pattern according to the inherent characteristic of each braiding machine. In order to solve the aforementioned problems, rotation number per minute is increased to advance productivity. However, it is not sufficient to maximize the productivity since increasing of rotation number per minute is limited.